<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
		/*全局reset,清除默认内外边距*/
			*{
				margin:0;
				padding:0;
			}
			div{
				border:1px solid red;
				width:200px;
				height:100px;
						   /*让左右外边距一样,进而实现居中*/
				margin:0 auto;
				/*margin:50px auto 0px;*/
				
				
				/*让div中的文字居中*/
				text-align: center;
				line-height: 100px;
			}
		</style>
	</head>
	<body>
		<div>
			123123
		</div>
	</body>
</html>
